Commercial micro-electro-mechanical systems (“MEMS”) now reach the sub-millimeter to micrometer size scale. There is, however, also great interest in nanometer scale electromechanical systems. Nanostructures are of great interest not only for their basic scientific richness, but also because they have the potential to revolutionize critical technologies.
Certain types of bearing structures are employed in MEMS and nano-electro-mechanical systems (“NEMS”) to allow for relative motion (e.g., linear or rotational) between two parts, but each has its limitations. For example, silicon-on-silicon sliding bearings generally have friction, lifetime, and debris issues. Gas bearings may have very low friction, but their design is typically complex and they generally are not operable in vacuum. For their part, ball bearings have size and wobble limitations.
Rotational actuators are of particular interest for several applications. For example, a dynamically tuned gyroscope, also known as a dry tuned gyroscope (“DTG”), typically includes a motor (e.g., an electromagnetic motor) that spins a shaft to which a rotor is attached. In some implementations, the shaft is supported by ball bearings. As mentioned, however, such ball bearings typically cannot be made small enough for some applications. In addition, they may consume greater amounts of power than desired due to undesirably high friction. Jeweled bearings and precisely machined pivots may be used instead, but, again, they typically increase the overall size of the DTG to larger than what is desired for many applications.
Rotational actuators that employ carbon nanotubes have been described. However, such actuators typically feature a rotor whose rotation axis is parallel to a top surface of the substrate. This arrangement is generally difficult to integrate with MEMS and NEMS processing, is difficult to manufacture, limits the applications of a device in which the actuator is employed, and limits the potential geometries for other features of the device (e.g., actuation and readout mechanisms).
Accordingly, needs exist for improved bearing structures and for methods of manufacturing and using the same.